Replacing Galvanized waste drain that ties in to Cast Iron Stack, with PVC ??

[Bill C.]

I need to replace a 1950's Drum Trap and Galvanized waste line from a Tub with PVC. I've done quite a bit of plumbing and know what I need to do to complete the job for the most part. But I have a concern with disconnecting the galvanized pipe from where it ties into the Cast Stack (right side of pic) as I haven't worked with cast much and it seems pretty fragile there. Attached is a pic of the joint I'm concerned with.

I want to cut the gal. pipe off at right side about 3 inches from the cast fitting and then remove that remaining piece with a pipe wrench, then transition back out of the cast fitting with a female PVC Adapter. But I'm worried about what might happen to the cast fitting while putting that much torque on the galvanized stub with pipe wrenches.

I'm thinking that If the 3 - 4 inch galv. pipe stub isn't too badly clogged where I'll cut it off there on the right side in front of the stack, then I'll just transition to PVC from there using a No-Hub / Fernco fitting, but I can't count on that as it's probably pretty clogged up.

I know it is hard to tell just from a picture, but do you guy's think the cast fittings in stack could be damaged by the force if I try to unscrew the gal. pipe from it? Of course I'd soak the threads with Liquid Wrench or Kroil first.

Appreciate any guidance you may have to offer.

Thanks,

Bill

 

[Cwhyu2]

You might be better off using a proflex coupling and connecting right to the short stubb of galvinized.

 

[Sponsor]

 

[Bill C.]

You might be better off using a proflex coupling and connecting right to the short stubb of galvinized.

Thank you, I will certainly use one if I end up transitioning to the PVC from the Gal. stubb.

My first choice however would be to completely remove the gal. pipe, then transition directly out of the cast using a female PVC Adapter.

So, I guess my question really is, could that female fitting that the gal. pipe ties in to at the stack, actually come loose from the stack by my putting torque on the gal. pipe with a wrench while trying to remove it. I assume that female fitting is joined to the cast stack via Oakum and Lead and not sure if it could possibly break loose from the stack?

Does anyone have any thoughts on that?

Thanks again in advance for any insight you may have to offer.

Bill

 

[Terry]

I assume that female fitting is joined to the cast stack via Oakum and Lead and not sure if it could possibly break loose from the stack?
Bill

If it's a lead and oakum joint, then putting a pipe wrench on the pipe and spinning it is likely to spin the pipe in the joint.
I would either cut the galvanized, or replace the lead joint.

 

[Bill C.]

If it's a lead and oakum joint, then putting a pipe wrench on the pipe and spinning it is likely to spin the pipe in the joint.
I would either cut the galvanized, or replace the lead joint.

Appreciate you clarifying that for me Terry. I was afraid that oakum joint might "fail" somehow if I put a lot of torque on the gal. pipe, but I'm not very familiar with working with cast at all, so your input will save me some headaches for sure ... thanks.

I was just trying to avoid using the gal. stub if possible to avoid any future issues with it clogging up. But it will be easy enough to get at in the future with a fernco on it if I can't unclog it with a snake (it's in a crawl space).

Thanks again for the input, it's much appreciated.

Bill